Moving media data storage devices such as disc drives are commonly used in a multitude of computer environments to store large amounts of data in a form that is readily available. Generally, a disc drive has one or more storage discs that are rotated by a motor at high speeds. Each disc has a data storage surface divided into data tracks where data is stored, such as in the form of magnetic flux transitions. A data transfer member is moved by an actuator to selected positions adjacent the data storage surface to sense the magnetic flux transitions in reading data from the disc, and to transmit electrical signals to induce the magnetic flux transitions in writing data to the disc.
The active elements of the data transfer member are supported by suspension structures extending from the actuator. The active elements are maintained a small distance from the data storage surface by a fluid bearing generated by fluid currents caused by the spinning discs. The term “fluid bearing” is synonymous with the term “air bearing” where the fluid utilized in the disc drive is air. Alternatively, the term “fluid bearing” is applicable to other embodiments utilizing a fluid other than air, such as helium.
A continuing trend in the data storage industry is ever-increasing the disc drive data storage capacity and processing speed while maintaining or reducing its physical size. Consequently, modern data transfer members and supporting structures are miniaturized, making them more susceptible to external excitation and unacceptable vibration. For instance, data storage densities being significantly higher than in the past, vibrations that were once ignored as negligible must now be addressed because of an overall increased sensitivity to vibration as a percentage of track width.
One source of excitation is the fluid currents from the spinning discs that impinge against the actuator and/or the rotating disc. During servo track writing operations, for example, vibrations from such excitation can result in actuator positional control errors and irregular servo track formatting, such as but not limited to track squeeze.
In some previously attempted solutions a shroud is used to encompass a portion of the disc as it rotates. The shroud has plates extending in close mating engagement with opposing data storage surfaces of the disc. The plates divert a greatest majority portion of the fluid currents away from the actuator to prevent them from impinging against the actuator and causing vibration. The fluid currents that flow through the shroud and ultimately impinge the actuator are straightened and non-turbulent. The pressurized fluid advantageously attenuates vibration in the disc.
The success with which the fluid excitation energy can be attenuated is directly related to minimizing the clearances between the stationary plates and the rotating disc. Ultimately, however, there is a finite limit to minimizing those clearances while ensuring that no contacting engagement occurs. In view of the limitations in the existing art, the claimed embodiments are directed to needed improvements in attenuating windage excitation energy.